Plant breeding is one of the oldest recorded accomplishments of mankind. The ability to breed plants is an important mark in man's movement from nomadic life to organized society. Today's food crops are essentially the result of mankind's primitive plant breeding attempts.
The practice of plant breeding has progressed to a science. Plant breeding became a science when genetic principles gave predictability to plant breeding. Plant breeding is basically man's conscious selection of genetic material instead of nature's selection of genetic material. Examples of the successes of plant breeding are the increased productivity of field crops, development of insect resistant crops and disease resistant crops. The progression of the plant breeding science has been slowed by natural factors. These factors include: the length of time necessary for development of a plant to its sexual maturity, the length of time to pollen viability and the length of time to maturity of the pollen receptor. Presently plants, specifically maize, can only be pollinated when a plant is sexually mature, pollen is viable, and pollen receptors are available. Thus, if plants are cross pollinated such that the pollen of one plant is used to pollinate a second plant, the sexual maturity of both plants have to be coordinated to permit pollination to occur as the time period of pollen viability is limited in most crops. One proposed method of increasing the efficiency and speed of plant breeding is to develop a system of storing pollen in a viable condition, a pollen bank. This would eliminate the need to coordinate the timing of sexual maturity of two plants and effectively eliminate one of the time factors in the plant breeding process. It eliminates plant breeding problems such as when pollen shed does not coincide with receptor maturity. Furthermore, a long term storage of viable pollen would provide an unique ability to conserve and manipulate genetic resources. The ability to retrieve viable pollen, obtained from an individual plant stored for long periods of time would provide great flexibility in plant breeding programs. Furthermore, in today's present environment of plant breeding research a pollen storage system provides a method to expand restrictive fragment length polymorphism research and transgenic biotechnology breeding programs by creating a germplasm bank of pollen which can be fingerprinted for future use in breeding programs.
Methods for storage of viable pollen have been tested and some pollen can be stored. However, pollen from many row crops, especially maize, has not been successfully stored. Research on maize pollen storage has shown some limited success using air flotation when large quantities of pollen are stored. An air flotation method of drying prepares maize pollen for medium to long term storage. The system is somewhat limited as it does not allow the stored pollen to be readily used in a commercial breeding program. The air flotation dries large quantities of pollen for storage. This stored pollen often has less than acceptable levels of viability when employed. This makes the use of stored pollen on a commercial basis unsatisfactory. There remains a need for a method and instrument for preparing pollen for individual plants which can be used and stored for use in research and commercial breeding programs. There remains a need for a method and instrument which can determine when pollen is properly prepared so that the pollen will be viable after storage in liquid nitrogen.